The invention relates to a dosimeter for ionizing radiation comprising a gas-filled measuring chamber surrounded by a casing in which there extends a number of electrode elements between which an electrical voltage exists during operation, the casing being provided with at least one entry window for the ionizing radiation.
Such dosimeters are already known from the Handbook on Synchrotron Radiation, Volume 1A, pages 323-328 by Ernst Eckhard Koch, published by North Holland Publishing Company, Amsterdam, New York, Oxford, 1983. A drawback of said known dosimeters is that application thereof is not readily possible in slit radiography equipment, where it has to be possible to measure and regulate the quantity of radiation per diaphragm section transmitted through a diaphragm slit at any instance during the production of a radiograph. An example of such slit radiography equipment, which does not, however, employ a dosimeter of the type described above, is described in the Dutch Patent Application 8,400,845. The known dosimeters are not designed to attenuate the radiation, the strength of which has to be measured, as little as possible and to prevent the formation of a visible X-ray shadow image of the dosimeter itself as far as possible. This latter is, however, of great importance in slit radiography equipment because the radiation transmitted through the dosimeter serves to produce the required radiograph. The shape and dimensions of the known dosimeters also make them unsuitable for application in slit radiography equipment.